• 한국지진공학회논문집
• /
• 제16권6호
• /
• pp.13-20
• /
• 2012

In this study, 5-story structures were designed in accordance with KBC2009 for inelastic time history analysis of RC IMRF. Bending moment-curvature relationship for beam and column was identified with fiber model and bending moment-rotation relationship for beam-column joint was calculated with simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The hysteretic behavior was simulated with three-parameter model suggested in IDARC program. The analytical results showed that the inelastic shear behavior of the joint could be neglected in the structural design for seismic design category C but the structure of category D did not satisfy the criteria of FEMA 356 for collapse prevention performance level.

• Steel and Composite Structures
• /
• 제7권5호
• /
• pp.355-376
• /
• 2007

The purpose of this study is to predict and investigate the time-dependent creep behavior of composite materials. For this, firstly the evaluation method for the modulus of elasticity of whole fiber and matrix is presented from the limited information on fiber volume fraction using the singular value decomposition method. Then, the effects of fiber volume fraction on modulus of elasticity of GFRP are verified. Also, as a creep model, the nonlinear curve fitting method based on the Marquardt algorithm is proposed. Using the existing Findley's power creep model and the proposed creep model, the effect of fiber volume fraction on the nonlinear creep behavior of composite materials is verified. Then, for the time-dependent analysis of a composite material subjected to uniaxial tension and simple shear loadings, a user-provided subroutine UMAT is developed to run within ABAQUS. Finally, the creep behavior of center loaded beam structure is investigated using the Hermitian beam elements with shear deformation effect and with time-dependent elastic and shear moduli.

• International journal of advanced smart convergence
• /
• 제9권4호
• /
• pp.120-123
• /
• 2020

The surveillance system to prevent crime and accidents in advance has become a necessity, not an option in real life. Not only public institutions but also individuals are installing surveillance cameras to protect their property and privacy. However, since the installed surveillance camera cannot be monitored for 24 hours, the focus is on the technology that tracks the video after an accident occurs rather than prevention. In this paper, we propose a system model that monitors abnormal behaviors that may cause crimes through real-time video, and when a specific behavior occurs, the surveillance system automatically detects it and responds immediately through an alarm. We are a model that analyzes real-time images from surveillance cameras and uses I3D models from analysis servers to analyze abnormal behavior and deliver notifications to web servers and then to clients. If the system is implemented with the proposed model, immediate response can be expected when a crime occurs.

• Advances in aircraft and spacecraft science
• /
• 제9권3호
• /
• pp.217-242
• /
• 2022

This paper proposes a novel time-domain homogenization model combining the viscoelastic constitutive law with Eshelby's inclusion theory-based micromechanics model to predict the mechanical behavior of the particle reinforced composite material. The proposed model is intuitive and straightforward capable of predicting composites' viscoelastic behavior in the time domain. The isotropization technique for non-uniform stress-strain fields and incremental Mori-Tanaka schemes for high volume fraction are adopted in this study. Effects of the imperfectly bonded interphase layer on the viscoelastic behavior on the dynamic mechanical behavior are also investigated. The proposed model is verified by the direct numerical simulation and DMA (dynamic mechanical analysis) experimental results. The proposed model is useful for multiscale analysis of viscoelastic composite materials, and it can also be extended to predict the nonlinear viscoelastic response of composite materials.

• Corrosion Science and Technology
• /
• 제21권2호
• /
• pp.158-169
• /
• 2022

The objective of this study was to investigate the electrochemical behavior and damage degree of metal surface under different conditions by performing a potentiodynamic polarization experiment using an electropolishing solution for UNS S31603 based on initial delay time and surface roughness (parameters). A second anodic peak occurred at initial delay time of 0s and 100s. However, it was not discovered at 1000s and 3600s. This research referred to an increase in current density due to hydrogen oxidation reaction among various hypotheses for the second anodic peak. After the experiment, both critical current density and corrosion current density decreased when the initial delay time (immersion time) was longer. As a result of surface analysis, characteristics of the potentiodynamic polarization behavior were similar with roughness, although the degree of damage was clearly different. With an increase in surface roughness value, the degree of surface damage was precisely observed. As such, electrochemical properties were different according to the immersion time in the electropolishing solution. To select electropolishing conditions such as applied current density, voltage, and immersion time, 1000s for initial delay time on the potentiodynamic polarization behavior was the most appropriate in this experiment.

• The Journal of Asian Finance, Economics and Business
• /
• 제7권9호
• /
• pp.63-74
• /
• 2020

This study investigates the behavior of foreign investors in the Stock Exchange of Thailand (SET) in the time of coronavirus disease 2019 (COVID-19) as to whether trading is abnormal, what strategy is followed, whether herd behavior is present, and whether the actions destabilize the market. Foreign investors' trading behavior is measured by net buying volume divided by market capitalization, whereas the stock market behavior is measured by logged return on the SET index portfolio. The data are daily from Tuesday, August 28, 2018, to Monday, May 18, 2020. The study extends the conditional-regression model in an event-study framework and extracts the unobserved abnormal trading behavior using the Kalman filtering technique. It then applies vector autoregressions and impulse responses to test for the investors' chosen strategy, herd behavior, and market destabilization. The results show that foreign investors' abnormal trading volume is negative and significant. An analysis of the abnormal trading volume with stock returns reveals that foreign investors are not positive-feedback investors, but rather, they self-herd. Although foreign investors' abnormal trading does not destabilize the market, it induces stock-return volatility of a similar size to normal trade. The methodology is new; the findings are useful for researchers, local authorities, and investors.

• 수산해양기술연구
• /
• 제59권2호
• /
• pp.125-134
• /
• 2023

The swimming behavior of pacific bluefin tuna (Thunnus orientalis) in the offshore sea cage of the brass fishing net was observed and analyzed by imaging sonar techniques. The cultured fish spent most of the time swimming a circular path along the circular cage wall and continued to swim only clockwise direction without completely changing the swimming direction during the 23-hour observation time. In addition, changed swimming behaviors were divided into four categories: (a) the behavior of a large group temporarily swimming in the opposite (counter clockwise) direction, (b) the behavior of a small group temporarily swimming in a small circular path, (c) the behavior swimming small circular path in the center of the cage, and (d) the behavior of a large group swimming across the center of the cage. The maximum swimming speed of the cultured fish was from 3.5 to 3.8 TL/s, the mode was from 1.2 to 1.4 TL/s and the swimming speed during the day time was faster than at night time. It was confirmed the cultured fish swam not only on the surface but also near the bottom net of the cage during the day, but swam mainly at the upper part of the cage at night.

• 한국산업보건학회지
• /
• 제29권1호
• /
• pp.98-107
• /
• 2019

Objective: This study was carried out to examine factors influencing job stress and health promotion behavior of medical doctors, who play the important role for improving people's health. The data were collected from 340 medical doctors working in clinic and hospitals in Daegu using self-administered questionnaires over the period from July 1 to August 15, 2018. Methods: A multiple regression model was used to study the factors influencing job stress and health promotion behavior of medical doctors. Results: This study showed that average job stress level of the subjects was 3.06 out of 5 point. The medical doctors with carrying out surgery and longer working time tend to have higher job stress level compared to other groups without surgery and having short working time. And medical doctors generally do not have good health promotion behavior and average level of practice of health promotion behavior of the subjects was 2.30 out of 5. The groups with high rate of quitting job and working in hospital tend to have lower practice level of health promotion behavior compared to other groups. And it also showed that the groups with higher the job satisfaction rate and vocational aptitude tended to have the higher level of practice of health promotion behavior compared with other groups. Conclusions: Medical doctors tend to have higher job stress level, whereas they have relatively lower health promotion behavior compared with people with other jobs. Thus, strengthening of health education and counselling for medical doctors and improvement of work environment considering job's characteristics is needed. In particular, the education for job stress management and health promotion in regular continuing education program organized by medical doctors's association should be strengthened.

• 문화기술의 융합
• /
• 제9권1호
• /
• pp.11-18
• /
• 2023

본 연구는 간호학과 신입생을 대상으로 전공 만족도, 시간 관리 행동, 자기효능감이 진로 준비 행동에 미치는 영향을 파악함으로써 간호학과 신입생의 진로 준비 행동 수준을 높이기 위한 교육 방법과 프로그램 개발의 기초자료를 제공하고자 한다. 자료수집은 2021년 10월 18일부터 10월 31일까지 J 도와 G 광역시에 소재한 대학교에서 간호학과 신입생 255명을 대상으로 편의표집 하였다. 수집된 자료는 SPSS 20.0 프로그램을 사용하여 기술통계, Pearson 상관계수, 다중회귀분석으로 분석하였다. 진로 준비 행동은 전공 만족도, 시간 관리 행동, 자기효능감과 양의 상관관계를 보였으며, 진로 준비 행동에 시간 관리 행동이 가장 큰 영향을 미치는 요인으로 총설명력은 18.8%로 나타났다. 본 연구 결과 간호대학생을 위한 시간 관리 프로그램을 개발 및 제공하여 신입생부터 시간 관리 능력을 키워나가야겠다.

• 융합보안논문지
• /
• 제22권2호
• /
• pp.3-8
• /
• 2022

보안 위협은 외부에서 발생하기도 하지만 내부에서 발생하는 비율이 더 높다. 특히 내부 사용자는 정보 서비스에 대한 정보를 인지하고 있기에 보안 위협에 의한 피해는 더욱 커진다. 이러한 환경에서 중요 정보 서비스에 접근하는 모든 사용자의 행위는 실시간으로 모니터링되고 기록되어야 한다. 그러나 현재 운영체제는 시스템과 Application 실행에 대한 로그만을 기록하고 있어, 사용자의 행위를 실시간으로 모니터링하기에는 한계가 있다. 이러한 보안 환경에서는 사용자의 비인가 행위로 인한 피해가 발생할 수 있다. 본 연구는 이러한 문제점을 해결하기 위하여, Linux 환경에서 사용자의 행위를 실시간으로 모니터링하는 아키텍처를 제안한다. 제안하는 아키텍처의 실효성을 확인하기 위하여 기능을 검증한 결과, 운영체제에 접근한 모든 사용자의 console 입력값과 출력값을 모두 실시간으로 모니터링하고 이를 저장한다. 제안한 아키텍처의 성능은 운영체제에서 제공하는 식별 및 인증 기능보다는 다소 늦지만, 사용자가 인지할 수준은 아닌 것으로 확인되어, 충분히 실효적이라고 판단되었다.